The invention relates generally to equipment useful in earth boring operations performed by a rotary drilling system and specifically to an improved portion of a rotary drilling system that allows for safe and convenient maintenance of the washpipe dynamic seals that are subject to heavy wear during drilling operations. More specifically, the present invention contemplates an improved washpipe assembly apparatus and a method for installing and removing the same.
A top drive well drilling apparatus typically includes a top drive system (TDS) connectable to the upper end of a drill string to drive the drill string rotatively and which moves upwardly and downwardly with the string during the drilling operation. The TDS includes a tubular main shaft, the lower end of which is threadedly connectable to the upper end of the drill string and through which drilling mud is delivered downwardly to the string and drill bit from a gooseneck and swivel assembly at the upper end of the unit. The unit further includes a motor to drive the main shaft rotatively as the well is drilled. A washpipe assembly comprising at least one dynamic seal and a tubular element is threadedly connected between the top of the main shaft and the bottom of the gooseneck/swivel assembly.
The washpipe assembly is located above the rotating TDS main shaft and below the stationary gooseneck. Drilling mud is pumped at high pressure through the gooseneck and washpipe assembly and into the main shaft. The dynamic seals of the washpipe assembly act as the main sealing elements between the connection of the washpipe assembly to each of the TDS main shaft and the gooseneck. During drilling operations these dynamic seals experience extreme wear and require frequent replacement.
Replacement of the dynamic seals requires an operator to disengage the connection of the washpipe assembly with each of the main shaft and the swivel/gooseneck, to remove the washpipe assembly and to install a replacement washpipe assembly. Installation and removal of the washpipe assembly are each accomplished in a similar manner. In conventional systems, both operations typically involve manually striking a nut that threadedly connects the washpipe assembly to the main shaft and manually striking a nut that threadedly connects the washpipe assembly to the swivel/gooseneck assembly. The manually striking is typically accomplished by a sledgehammer, thereby imparting an impact torque to either engage or disengage the nuts. Repeated application of such impact torque may be necessary, particularly when the connection must be disengaged after extended exposure to the extreme stresses and environmental conditions of the drilling environment. In the best of circumstances, this operation is unsafe and time-consuming. Moreover, because the torque applied is uncontrolled, i.e. not measured, a determination of whether the nuts of the washpipe assembly are fully engaged or disengaged is left to the judgement of the operator that is installing or removing the washpipe assembly. Thus, increasing the likelihood of operator error and subsequent damage to the rig.
Accordingly, a need exists for a new apparatus and method for installing a washpipe assembly in a safe and controlled manner.
The present invention provides a drilling apparatus designed to allow for the controlled, i.e. measured, application of torque to a washpipe assembly during installation of the washpipe assembly to each of a main shaft and a gooseneck. In one embodiment, the washpipe assembly generally comprises a washpipe fluid conduit, at least one dynamic seal, a gooseneck geared nut mating connector for threadedly connecting the washpipe assembly to a stationary gooseneck connector, and a packing box geared nut mating connector for threadedly connecting the washpipe assembly to a rotatable main shaft connector. In addition, a torque driver is provided to apply a suitable torque to each of the mating connectors of the washpipe assembly to sealingly interconnect the washpipe assembly to the stationary gooseneck connector and to the rotatable main shaft connector. It has been found that this combination allows drilling mud to be pumped through the stationary gooseneck, the washpipe assembly, the rotating main shaft, the drill stem, the drill string and the drill bit during drilling operations.
Although any suitable dynamic seal may be utilized in the present invention, in one embodiment the dynamic seal is designed to provide a fluid seal between the washpipe assembly and each of the threaded connections of the gooseneck and the main shaft. For example, the dynamic seals may comprise an elastomeric o-ring type seal.
In one alternative embodiment, the torque driver comprises an drive shaft housing mounted on a side of a washpipe bonnet and aligned in a manner roughly parallel to a longitudinal axis of the main shaft. In such an embodiment, the drive shaft housing partially encloses a drive shaft that is both slidable along and rotatable about its own axis. A torque transfer mechanism, such as a pinion gear is slidably affixed to a portion of the drive shaft that is interior to the washpipe bonnet. The pinion gear is disposed at a convenient vertical position along the drive shaft and secured thereto by a fastener such as, for example, a thumb screw. The drive shaft may have any convenient cross section, such as square, rectangular, triangular or pentagonal, among other cross sections. Likewise, any torque transfer mechanism suitable for transferring an externally applied torque to the washpipe assembly, such as a drive rod or chain linkage may be utilized.
In yet another exemplary embodiment, the torque driver comprises an optional torque multiplier and a manual torque wrench attached thereto. In such an embodiment, torque is applied manually through the torque wrench. Although a manual drive system is described above, any drive system capable of controllably and reproducibly applying a specified torque to the mating connections of the washpipe assembly may be utilized. An exemplary alternative embodiment includes a drive shaft with a torque drive motor having a coupling. For example, the torque drive motor may be an air motor, a hydraulic motor or an electric motor. Another exemplary alternative embodiment includes a hydraulic cylinder having a connective means. A further exemplary alternative embodiment includes a torqueing sleeve and the TDS main motor.
In still another exemplary embodiment, an optional bracket adjacent the washpipe bonnet allows a washpipe positioning mechanism to be rotatably connected to the washpipe bonnet to move the washpipe assembly into and out of an opening in the washpipe bonnet.
In still yet another embodiment, the present invention is directed to a method of installing and removing a washpipe assembly from a drill rig. In one such embodiment, the method involves engaging and disengaging the threaded connections between the washpipe assembly and each of the gooseneck and the main shaft, utilizing the washpipe assembly described above.